The rates and direction of shear strain from geodetic data and the direction of slip from earthquake mechanism studies in New Zealand are
in good agreement with plate tectonic theory. The relative motion of
the Pacific and Indian plates in the last 100 years has been accommodated by distributed strain in a belt at least 100 km wide crossing New Zealand from north-east to south-west. Strain rates within this belt exceed
3 x 10-7/y and average 5 x 10-7/y in Marlborough. Under the eastern North Island and northern part of the South Island the Pacific plate underthrusts the overlying belt of deformation. Large thrust earthquakes are episodically generated, perhaps by locking of the thrust. Not all relative plate movement is transformed into displacement on faults - a substantial fraction is taken up by aseismic and anelastic deformation within the plate boundary zone. The relative proportion of aseismic and seismic deformation may vary in different regions.